Transmission Shift Element Pressure Curve Adaptation for Precise Engagement

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for adapting the pressure characteristic curve of friction-locking shift elements in transmissions lack precision in adjusting the touch and contact points, leading to suboptimal engagement quality.

Innovation Solution

A method that adjusts the pressure characteristic curve by actuating the shift element with a rapid filling pressure for a reduced duration, followed by a waiting pressure, and iteratively adjusting the waiting pressure until the reaction matches the desired rapid filling time adaptation, allowing precise adaptation of touch and contact points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rapid filling time of a friction-locking shift element is adapted using conventional methods, then the engagement process can be improved, but the precision in adjusting the touch and contact points on the pressure characteristic curve remains insufficient

Engineering Contradiction:

Improveengagement qualityVSAvoidtouch and contact point adjustment precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The pressure characteristic curve is segmented into distinct phases: rapid filling phase, filling equalization phase, and further phases. The method specifically targets and adapts characteristic points (touch point and contact point) within these segments, allowing precise adjustment of each phase's contribution to the overall engagement process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The method changes pressure parameters at specific characteristic points on the pressure characteristic curve. By adapting the pressure values at the touch point and contact point separately from the rapid filling pressure, the invention achieves precise control over the engagement process, resolving the contradiction between overall engagement quality and specific point adjustment precision.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the pressure actuation is simplified to use only rapid filling pressure adaptation, then the control process becomes easier, but the ability to precisely control touch and contact points is lost

Engineering Contradiction:

Improvecontrol process simplicityVSAvoidpressure characteristic curve adaptation precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The pressure actuation is segmented into multiple independent adaptation parameters: rapid filling pressure, touch point pressure, and contact point pressure. This segmentation allows the control process to maintain simplicity by treating each parameter separately while achieving high precision in the overall pressure characteristic curve adaptation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The method performs preliminary adaptation of the rapid filling time first, then uses this adapted value as a basis for subsequent precise adaptation of the touch and contact points. This preliminary action simplifies the overall process by establishing a foundation before fine-tuning specific characteristic points.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If the actuation duration is reduced below the adapted rapid filling time, then the touch and contact points can be precisely adjusted, but additional control steps are required

Engineering Contradiction:

Improvecharacteristic point adjustment precisionVSAvoidcontrol steps

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The method dynamically adjusts the actuation duration based on the adapted rapid filling time, using a defined relationship (actuation duration = adapted rapid filling time - defined period of time). This dynamic adjustment allows precise control of characteristic points while the control unit automates the timing calculations, preventing excessive complexity in the control steps.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The method uses feedback from the adapted rapid filling time to determine the appropriate actuation duration for adjusting touch and contact points. By continuously referencing the adapted rapid filling time, the system maintains precision while following a systematic, feedback-driven control sequence that manages complexity.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12607258B2Method for adapting a pressure characteristic line of a friction-locking shifting element of a transmission, and controller

Publication Date: 2026.04.21 ZF FRIEDRICHSHAFEN AG

AI summary

A method for adapting a pressure characteristic curve of a friction-locking shift element of a transmission of a motor vehicle includes actuating the shift element using a rapid filling pressure for a first time, shorter than an adapted rapid filling time by a defined period of time. The method further includes subsequently actuating the shift element using a waiting pressure for a waiting time, the waiting pressure being lower than the rapid filling pressure. The method further includes subsequently actuating the shift element using the rapid filling pressure during a second time, equal to the defined period of time, and ascertaining a reaction of the transmission to adaptation. Additionally, the method includes determining, when the reaction of the transmission to the adaptation corresponds to a reaction to the rapid filling time adaptation, a pressure at a characteristic point on the curve being adapted as the waiting pressure.